Antennariidae

Frogfishes

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Introduction

Frogfishes of the family Antennariidae are typically small, globose anglerfishes easily distinguished from members of allied families by the presence of three well-developed dorsal spines, laterally directed eyes, a large, anterodorsally directed mouth, and a short, laterally compressed body (Pietsch, 1981). They share with other familes of the teleost order Lophiiformes a peculiar and unique mode of feeding that is characterized most strikingly by the structure of the first dorsal spine, which is placed out on the tip of the snout and modified to serve as a luring apparatus.

Frogfishes spend the greater part of their lives squatting on the bottom in shallow to moderately deep water, or as in the case of the single genus Histrio, clinging to floating sargassum. Despite their rather sedentary nature, all are voracious carnivores that wait patiently for smaller fishes or crustaceans to pass by, while they wriggle their bait to entice prey close to their cavernous mouths. Antennariids occur in all major tropical seas of the world except the Mediterranean. The family consists of 12 genera and 43 species.

Characteristics

Diagnosis

A lophiiform family unique and derived in having a greatly enlarged third dorsal spine (and associated pterygiophore), as well as a shortened body involving numerous associated specializations but reflected most strikingly by a sigmoid vertebral column (see Pietsch, 1981, figs. 12, 22-35, 41; 1984).

The familiy is further distinguished from all other families of the order by having the following combination of character states: body laterally compressed; mouth strongly oblique to vertical; eyes lateral; posteromedial process of vomer compressed, keel-like; distance between lateral ethmoids considerably less than that between lateral margins of sphenotics; postmaxillary process of premaxilla spatulate; ectopterygoid triradiate; palatine teeth present; dorsal head of quadrate narrow, narrower than ventral margin of metapterygoid; interhyal with a medial, posterolaterally directed process; basihyal present; branchiostegal rays 2 + 4 ; opercle reduced, the width equal to or less than 25% the length of suspensorium; pharyngobranchial I simple (absent in Lophiocharon and Histiophryne); spinous dorsal of 3 cephalic spines; illicial pterygiophore and pterygiophore of third dorsal spine with highly compressed, blade-like dorsal expansions; illicial bone not retractable within an illicial cavity; 3 pectoral radials; pectoral-fin lobe not membranously attached to rays of pelvic fin; pectoral fin single, the rays not membranously attached to side of body; pelvic fin of 1 spine and 5 rays. (Pietsch, 1981, 1984)

Description

Body short, globose, laterally compressed; mouth large, the upper and lower jaws with 2-4 more or less irregular rows of small, villiform teeth; opercular opening restricted to a small, elongate, tube-like opening immediately ventral to, or posterior to, base of pectoral fin (prolonged posteriorly, siturated halfway between base of pectoral lobe and anal fin, or reaching base of anal fin, in some species of Antennarius); spinous dorsal fin of 3 cephalic spines, the anteriormost spine (illicium) free and modified as a lure; distinct fleshy bait or esca usually present, but absent in Lophiocharon lithinostomus and Echinophryne; second and third dorsal spines usually more or less erect (laid back and bound down to surface of cranium by skin of head in Histiophryne), usually widely separated from each other and from soft-dorsal (connected to each other and to soft-drosal by skin in Lophiocharon and in some species of Antennarius); posterior end of pterygiophore of illicium usually cylindrical in cross section (dorsoventrally flattened and expanded laterally in Tathicarpus); pectoral lobe elongate, leg-like, usually broadly attached to side of body (free for most of its length in Histrio and Tathicarpus); skin usually coverd with close-set dermal spinules (spinules usually bifurcate, simple in Histiophryne, reduced, minute, or absent in Nudiantennarius and Histrio, absent in Phyllophryne and Rhycherus); cutaneous filaments or appendages nearly always present; mesopterygoid usually absent, present in Antennarius, Nudiantennarius, Antennatus, and Histrio; epural usually absent, present in Antennarius, Nudiantennarius, Antennatus, and Histrio; pseudobranch usually absent, present in Antennarius, Histrio, and Tathicarpus; swimbladder usually present, absent in Kuiterichthys and Tathicarpus.

Vomer and palatine well-toothed; pharyngobarnchial I, if present (absent in Lophiocharon and Histiophryne), usually toothless (a single tooth-bearing plate present on only right side of 73-mm specimen of Allenichthys examined osteologically); pharyngobranchials II and III well toothed; epibranchials usually toothless (a row of 6-11 teeth present on epibranchial I of Tathicarpus; a single tooth-bearing plate, or small remnants of a tooth-plate, present on epibranchial I of some specimens of Antennarius, Antennatus, Kuiterichthys, Allenichthys, Echinophryne, Phyllophryne, and Rhycherus); ceratobranchials I-IV usually toothless (a single tooth-plate, often reduced to a small remnant, present on ceratobranchial I of Allenichthys, some species of Echinophryne and Rhycherus); ceratobranchial V with 2-6 more or less irregular rows of teeth; hypobranchials II and III usually bifurcate proximally (hypobranchial II often reduced and simple in Kuiterichthys, Allenichthys, Echinophryne, Rhycherus, and Histiophryne); ossified basibranchial only rarely present; vertebrae 18-23, caudal centra 12-18, dorsal rays 10-16, anal rays 6-10, pectoral rays 6-14; usually only 7 innermost rays of caudal fin bifurcate (all rays bifurcate in Antennarius, Antennatus, Allenichthys, Lophiocharon, and Rhycherus; all simple in Tathicarpus).

Color and color pattern highly variable, with two extremes (the entire range of which can be assumed by living individuals of many species during a period of days or weeks, the specimens often changing radically upon preservation); a more common light-color phase with light-tan to yellow, orange, light-brown, or rust background often overlaid with black, brown, pink, or bright-yellow streaks, bars, and/or spots o the head, body, and fins; and a dark-color phase with green, dark-red, dark-brown, to black background with streaks, bars, and/or spots often (but not always) showing through as deeper black, tips of rays of paired fins often white.

Juveniles and adults benthic in 0-300 m, with the single exception of Histrio, which is pelagic in floating sargassum weed; adults of some species attaining a standard length of at least 35 cm; occurring in all major tropical seas of the world except the Mediterranean; 12 genera and 43 species.

Discussion of Phylogenetic Relationships

Pietsch and Groebecker (1987) unsuccessfully attempted to provide a cladistic analysis of the phylogenetic relationships of antennariid genera. In particular, monophyly for the 24 species of the genus Antennarius was not established. Despite considerable effort, they were unable to identify a single clearly derived feature shared by all included taxa. Thus, Pietsch and Grobecker (1987) defined the genus by a suite of what are believed to be primitive features.

Evidence indicates that Antennarius is the least derived member of the family (Pietsch, 1984). All of the known characters of systematic importance found among the 12 genera (at least all of those characters for which relative primitiveness of states could be reasonably hypothesized) appear to be present in Antennarius in the primitive state. Each of the remaining 11 genera possesses at least two, and in some cases as many as nine, apomorphic character states (autapomorhpic states included) that indicate its derived position relative to Antennarius.

Whereas a hypothesis of monophyly for each of the remaining 11 genera can be supported (six genera being monotypic and none containing more than three species), their phylogenetic relationships as elucidated by cladistics remain largely unknown, and they are here sequentially arranged solely on the basis of increasing relative specialization. No group of two or more genera possesses any convincing synapomorphy that does not also occur within lophiiform taxa lying outside the group in question.

Distribution

Frogfishes are widely distributed in tropical waters of all four major marine faunal realms of the world. By far the majority of the species, however, and all but three of the genera, are confined geographically to the Indo-Australian Archipelago. The family is well represented in the Gulfs of California and Mexico, the Red Sea, and the Persian Gulf, but like all antennarioids it is unknown from the Mediterranean Sea. With the possible exception of Histrio, Antennarius, with its 24 species, is the only circumglobal genus. In the Western Atlantic it ranges from Long Island, New York, to the southern-most coast of Brazil, and in the Eastern Atlantic, form the Azores and the coast of Senegal to South-West Africa. In the Indo-Pacific it ranges from the tip of South Africa and the Red Sea eastward to virtually all oceanic island groups of the South Pacific, and from southern Japan to New Zealand and the tropical waters of Australia. In the eastern Pacific Ocean, Antennarius occurs throughout the Gulf of California to northern-most Peru and the Galápagos Islands, with two records from Isla San Félix, off central Chile.

The genus Antennatus, embracing two species, occurs throughout the tropical Indo-Pacific and Easter Pacific oceans, from East Africa to the Gulf of California, and the coast of Mexico and Central and South America as far south as Colombia and the Galápagos Islands. The monotypic genus Histrio is sympatric with sargassum throughout the Atlantic and Indo-Pacific oceans, with confirmed captures made as far east as Guam in the north and Tonga in the south. Histiophryne occurs from Taiwan, the Philippines, and the Moluccas to the southern coast of Australia. Lophiocharon is found throughout the islands of the Philippines and Indonesia to the northern coast of Western Australia, Northern Territory, Gulf of Carpentaria, and the northeastern coast of Queensland. Tathicarpus is restricted to the southern coast of New Guinea and to Australia about as far south as Perth in the west and Brisbane in the east. Allenichthys occurs only along the shores of Western Australia below about 21° S latitude, with a single record from Port Lincoln, South Australian. Nudiantennarius is known from only four specimens collected off Luzon in the Philippines and at Ambon in the Moluccas, Indonesia. All four remaining genera of the family are restricted to the subtropical coastal waters of Australia and Tasmania below about 30° S latitude.

Key to the Known Genera

This key works by progressively eliminating the most derived taxon, and for that reason should always be entered from the beginning. All features listed for each species-group must correspond to the specimen being keyed; if not, proceed to the next set of characters. The figures accompanying the key are diagrammatic; dermal spinules and cutaneous appendages (with minor exceptions) are not shown.

6. A row of translucent to transparent ocelli on membranes of caudal fin, 1 between each 2 rays (best observed by spreading rays); anterior tip of pterygiophore of illicium upturned; second dorsal spine connected to base of third spine, the third spine connected to soft-dorsal fin by skin; all rays of soft-dorsal and caudal fins bifurcate; caudal peduncle absent, the membranous posteriormost margin of soft-dorsal and anal fins attached to body at base of outermost rays of caudal fin; pectoral rays 9 (Lophiocharon Whitley, 1933, Philippines to tropical Australia)

7. Illicium more than twice the length of second dorsal spine, the latter reduced (length less than 9% SL), recurved with a narrow , tapering distal tip; caudal peduncle absent, the membranous posteriormost margin of soft-dorsal and anal fins attached to body at base of outermost rays of caudal fin; all rays of caudal fin bifurcate; dorsal rays 15 or 16, anal rays 8 (Allenichthys Pietsch, 1984, Western and South Australia)

10. Skin thick and firm, everywhere covered with extremely close-set dermal spinules (in some cases, the spinules closely clustered to form slightly raised, wart-like patches; naked areas between pores of acoustico-lateralis system absent); illicium more or less tapering to a fine point, an esca absent on only barely distinguishable; third dorsal spine more or less immobile, bound down to surface of cranium by skin of head; caudal peduncle absent, the membranous posteriormost margin of soft-dorsal and anal fins attached to body at base of outermost rays of caudal fin; all rays of caudal fin bifurcate (Antennatus Schultz, 1957, Indo-Pacific and Eastern Pacific oceans)

11. Skin covered with dermal spinules, but obvious only on head between and on surface of second and third dorsal spines (elsewhere the spinules difficult to detect without microscopic aid); illicium about one-third the length of second dorsal spine, the latter long, 19.5-28.1% SL, without posterior, membranous connection to head; outermost rays of caudal fin simple, only the 7 innermost bifurcate; pectoral rays 9 (Nudiantennarius Schultz, 1957, Philippines and Moluccas)

Page: Tree of Life
Antennariidae. Frogfishes.
Authored by
Theodore W. Pietsch.
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